Patient Education - Endocrine Encyclopedia
Endocrine Surgery Encyclopedia
 Definition:
Hyperthyroidism is an imbalance of metabolism caused by overproduction of thyroid
hormone.
Alternative Names: Thyrotoxicosis; Overactive thyroid
Causes, incidence, and risk factors:
The thyroid gland is located in the neck. It produces several hormones which control
the way that every cell in the body uses energy (metabolism). The thyroid is part
of the endocrine system.
Hyperthyroidism or thyrotoxicosis occurs when the thyroid releases too many of
its hormones over a short (acute) or long (chronic) period of time. Many diseases
and conditions can cause this problem, including:
- Graves' disease
- Non-cancerous growths of the thyroid gland or pituitary gland
- Tumors of the testes or ovaries
- Inflammation (irritation and swelling) of the thyroid due to viral infections
or other causes
- Ingestion of excessive amounts of thyroid hormone
- Ingestion of excessive iodine
Graves' disease accounts for 85% of all cases of hyperthyroidism.
Related topics:
- Painless (silent) thyroiditis
- Factitious hyperthyroidism
- Hypothyroidism
- Graves' disease
Symptoms:
- Weight loss
- Increased appetite
- Nervousness
- Restlessness
- Heat intolerance
- Increased sweating
- Fatigue
- Frequent bowel movements
- Menstrual irregularities in women
- Goiter (visibly enlarged thyroid) may be present
Additional symptoms that may be associated with this disease:
- Weakness
- Sleeping difficulty
- Clammy skin
- Skin blushing or flushing
- Bounding pulse
- Nausea and vomiting
- Lack of menstruation
- Itching - overall
- Heartbeat sensations
- Hand tremor
- Hair loss
- Diarrhea
- Breast development in men
- High blood pressure
- Protruding eyes (exophthalmos)
Signs and tests:
Vital signs (temperature, pulse, rate of breathing, blood pressure) show increased
heart rate. Systolic blood pressure may be elevated. Physical examination may reveal
thyroid enlargement or goiter.
Laboratory tests that evaluate thyroid function:
- Serum TSH is usually decreased
- T3 and free T4 are usually elevated
This disease may also alter the results of the following tests:
- Vitamin B-12
- TSI
- Triglycerides
- RT3U
- Radioactive iodine uptake
- Glucose test
- Cholesterol test
- Antithyroglobulin antibody
Treatment:
Treatment varies depending on the cause of the condition and the severity of symptoms.
Hyperthyroidism is usually treated with antithyroid medications, radioactive iodine
(which destroys the thyroid and thus stops the excess production of hormones), or
surgery to remove the thyroid.
If the thyroid must be removed with radiation or surgery, replacement thyroid
hormones must be taken for the rest of the person's life.
Beta-blockers like propranolol are used to treat some of the symptoms including
rapid heart rate, sweating, and anxiety until the hyperthyroidism can be controlled.
Support Groups:
Expectations (prognosis):
Hyperthyroidism caused by Graves' disease is usually progressive and has many associated
complications, some of which are severe and affect quality of life.
These include complications caused by use of radioactive iodine, surgery, and
medications to replace thyroid hormones. However, hyperthyroidism is generally treatable
and rarely fatal.
Complications:
- Cardiac complications include rapid heart rate, congestive heart failure, and atrial
fibrillation.
- Thyroid crisis or "storm" is an acute worsening of the symptoms of
hyperthyroidism that may occur with infection or stress. Fever, decreased mental
alertness, and abdominal pain may occur, and immediate hospitalization is indicated.
- Hyperthyroidism increases the risk for osteoporosis.
- There may be complications related to surgery, including visible scarring of
the neck, hoarseness due to nerve damage to the voicebox, and a low calcium level
because of damage to the parathyroid glands.
- Complications may be related to replacement of thyroid hormones. If too little
hormone is given, symptoms of under-active thyroid can occur including fatigue, increased
cholesterol levels, mild weight gain, depression, and slowing of mental and physical
activity.
Calling your health care provider:
Call your health care provider if you have symptoms which could be caused by excessive
thyroid hormone production. If the symptoms are associated with a rapid, irregular
heartbeat, dizziness, or change in consciousness, go to the emergency room or call
the local emergency number (such as 911).
Call your health care provider if treatment for hyperthroidism induces symptoms
of under-active thyroid, including mental and physical sluggishness, weight gain,
and depression.
Prevention:
There are no general prevention measures to prevent hyperthyroidism.
Review Date: 8/6/2004
Reviewed By: Aniket R. Sidhaye, M.D., Division of Endocrinology and Metabolism, Johns
Hopkins University School of Medicine, Baltimore, MD. Review provided by VeriMed
Healthcare Network.
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